17. All the Time in the World

Complete story — includes the ending

Flashbacks reveal Sydney's earlier life-events; Project Christmas building-block testing; hearing her mother died; discussing majors with Francie Calfo; " CIA " recruitment; working for Credit Dauphine. Vaughn finds Sydney unconscious, reviving her. Deal successful, Peyton reveals The Horizon. Sark asks about global genocide. Sloane confirms, revealing two nuclear missiles. Deducing Sloane has another ally, Sydney has Marshall hacks banks, phones, satellites, locating Peyton, who Rachel knows fears snakes. Peyton says Sloane's targeting two major cities, naming his Hong Kong ally. In Mongolia, Sloane excavates Rambaldi's tomb; the Horizon collects red Mueller fluid. Sydney takes the Horizon, instigating a stand-off with Sark holding Vaughn and Jack. Sloane shoots Jack; Sydney kills Sloane, who falls into a Mueller-red pool. Sark escapes with the Horizon. Jack urges Sydney to go stop Irina Derevko. Irina has Sark target London and D.C.. Irina tells Sydney, power is the only currency; through Rambaldi, they'll live forever. Sydney and Irina fight. Vaughn shoots Sark for launch abort codes. Restored to eternal life, Sloane offers to heal Jack, who detonates explosives, entombing Sloane forever. Still struggling, Irina falls to her death trying to grab the Horizon. Nadia's ghost mocks Sloane, who has "all the time in the world." Series epilogue: Seven year-old Isabelle builds sand castles by the ocean as "Uncle Dixon" arrives. Vaughn greets the Deputy Director. Sydney cradles toddler son, Jack. Dixon asks Sydney for field assistance, but Vaughn suggests dinner first. Isabelle unpacks and effortlessly stacks Project Christmas blocks – then nonchalantly knocks them down to join Sydney, Vaughn and Dixon for a walk on the beach.